What are the Stall Speeds for "H" and "Z" Torque Converters?

[[email protected]]

Will greatly appreciate finding out the different Stall Speed ratings for Torque Converters used in the VW Auto Transmission?

I know the "H" and "Z" code letters were used in Vanagon applications and have the higher stall speeds, just don't know the actual ratings.

Also, am aware of there being a "C" code TC and "D" code TC (I think those may have been for Type 3 VWs with auto trans, and possibly the 411/412 auto trans vehicles).

FYI: I will be matching a 2.0L Type 4 engine with the "003" stock VW three speed auto transmission (using a Type 4 Flex Plate).

Thank you in advance for your input on the different actual Stall Speeds.

Please volunteer what you know.

[Wildthings]

The stall speed of both the "H" and "Z" is specified as something like 2750 rpm, IIRC. My experience is that any fairly stock VW boxer engine does better with the higher stall speed these two torque converters offer.

[VicVan]

I don't know what stall speed is, so I looked it up.

What is Stall Speed?

Stall speed is the speed at which the converter holds back or limits the engine speed if the transmission output is prohibited. When your torque converter prevents the power transfer from your engine to your transmission, it increases the engine’s RPM stalls. For example, when you press down on your gas pedal, the stall speed is the gap between where your vehicle idles and begins to move. The more stall speed you have, the more pressure you have to put on the gas pedal before your car begins to move.

Source: https://revmaxconverters.com/part-understanding-torque-converter-stall-speeds/

The problem is, I have no clue what that means. So my question is: what is stall speed?
_________________
'90 Little Blue Truck, 2WD auto, FAS GenV 2.0 NA (AVH)

[skills@eurocarsplus]

[VicVan]

Thanks Skills for taking the time. It's very clear!
I grew up with manual transmissions, and the Vanagon is my first automatic. I think it's the last component of the van that is a black box to me, so I'm happy to understand a bit better how it works.

So I imagine you want stall speed close to maximum torque, or if that value is too high (high-revving gasoline engine for example), at least at an RPM where a significant amount of torque is produced. That being said, the lower RPM the better ?
_________________
'90 Little Blue Truck, 2WD auto, FAS GenV 2.0 NA (AVH)

[Wildthings]

VW proved with the Type 4 cars that having too low of a stall speed was a really good way to kill performance and burn up transmissions. Over the decades VW reluctantly increased the stall speeds of their TCs from being around 1800 all the way to 2750 rpms, with the performance increasing every step along the way.

There is a note in the Vanagon Bentley recommending the use of the later TCs on earlier vehicles. Just going from a "D" torque converter to a "Z" or "H" torque converter can make a big difference, so unless you are installing an engine that makes 50% or more bottom end torque than the original WBXer going to a lower stall speed RC is not likely to give satisfactory performance.

[khughes]

Well it kind of depends on which "world" you're talking about. In the drag racing world Hughes Converters, for example, define stall speed as:

Torque converter stall speed is the maximum amount of engine RPM that can be achieved in an automatic transmission-equipped vehicle while the transmission is in a forward operating range without generating any driveshaft motion.

For drag racing, stall speed is usually selected to allow the RPM to reach the maximum torque RPM for launch (i.e. in the sweet spot for the cam, or to get up on boost for turbo cars) before the converter basically locks up and overcomes brakes (foot or trans brakes) and the car moves. While still ensuring optimal torque is maintained at shift points as well.

Granted, not a huge danger with a wbx'er
_________________
'86 Westy FAS GenV Turbo (Marvin)

[skills@eurocarsplus]

[kamzcab86]